Ask Dr. K: Chronic stress causes cells to age

Dear Dr. K: For years I've heard that chronic stress is bad for your health, but recently I heard something that made me take this seriously: Stress causes our cells to age faster. Is this really true?

Dear Reader: I'll bet you're talking about research showing that stress affects the telomeres. These structures are a part of every cell in our body. And if that's what you're asking about, it really is true. In fact, it's part of a discovery so important that it was honored with the Nobel Prize.

The telomeres are the ends of the chromosomes, the structures inside each cell that contain the genes. Over time, the telomeres get shorter. When they get short enough, the cell dies.

What does this have to do with stress? Chronic stress leads to shorter telomeres. The first study that showed this was published in 2004. The senior author, professor Elizabeth Blackburn of the University of California-San Francisco, was one of the scientists awarded the Nobel Prize. The study included mothers caring for chronically ill children. The women under the greatest stress had the shortest telomeres. It was as if their cells were 10 years older than the women under the least stress.

Since that study, many other studies of people of all ages, in different kinds of stressful situations, have come to the same conclusion: Chronic stress leads to shorter telomeres -- to cells that are "older" and closer to the end of their lives.

Most of these studies have been done in older adults, but some have been done in younger adults. For example, young pregnant women exposed to major stress during their pregnancies (such as from the illness or death of a parent) have shorter telomeres than young pregnant women with relatively stress-free pregnancies.

This even is true in children. Children exposed to lots of violence appear to develop shorter telomeres. Chronic stress in childhood, like physical abuse, can lead to shorter telomeres that remain short into middle age.

What does having "older" cells have to do with health? A growing number of studies show that people with shorter telomeres are much more likely to develop certain types of cancers, heart disease and dementia. In fact, some experts are predicting that we will soon be routinely measuring the length of a person's telomeres as part of assessing his or her health.

Could stress-reduction techniques slow cellular aging? In a review article published last year in the scientific journal Nature, professor Blackburn says the answer probably is "yes." She describes preliminary studies of stress reduction combined with increased physical activity and dietary changes. It appears from these studies that the telomere shortening may be slowed.

The story of telomeres and cell aging is a prime example of how scientists interested in how our cells work can make unexpected discoveries about what makes us sick — and how to prevent it.

Dr. Komaroff is a physician and professor at Harvard Medical School. See his website to send questions and get additional information: www.AskDoctorK.com.